scholarly journals New Chemical Scaffolds for Human African Trypanosomiasis Lead Discovery from a Screen of Tyrosine Kinase Inhibitor Drugs

2014 ◽  
Vol 58 (4) ◽  
pp. 2202-2210 ◽  
Author(s):  
Ranjan Behera ◽  
Sarah M. Thomas ◽  
Kojo Mensa-Wilmot
Keyword(s):  
Tyrosine Kinase ◽  
Protein Tyrosine Kinase ◽  
Human African Trypanosomiasis ◽  
Kinase Inhibitor ◽  
New Drugs ◽  
Proof Of Concept ◽  
African Trypanosomiasis ◽  
Lead Discovery ◽  
Content Type ◽  
Growth Inhibitory

ABSTRACTHuman African trypanosomiasis (HAT) is caused by the protozoanTrypanosoma brucei. New drugs are needed to treat HAT because of undesirable side effects and difficulties in the administration of the antiquated drugs that are currently used. In human proliferative diseases, protein tyrosine kinase (PTK) inhibitors (PTKIs) have been developed into drugs (e.g., lapatinib and erlotinib) by optimization of a 4-anilinoquinazoline scaffold. Two sets of facts raise a possibility that drugs targeted against human PTKs could be “hits” for antitrypanosomal lead discoveries. First, trypanosome protein kinases bind some drugs, namely, lapatinib, CI-1033, and AEE788. Second, the pan-PTK inhibitor tyrphostin A47 blocks the endocytosis of transferrin and inhibits trypanosome replication. Following up on these concepts, we performed a focused screen of various PTKI drugs as possible antitrypanosomal hits. Lapatinib, CI-1033, erlotinib, axitinib, sunitinib, PKI-166, and AEE788 inhibited the replication of bloodstreamT. brucei, with a 50% growth inhibitory concentration (GI50) between 1.3 μM and 2.5 μM. Imatinib had no effect (i.e., GI50> 10 μM). To discover leads among the drugs, a mouse model of HAT was used in a proof-of-concept study. Orally administered lapatinib reduced parasitemia, extended the survival of all treated mice, and cured the trypanosomal infection in 25% of the mice. CI-1033 and AEE788 reduced parasitemia and extended the survival of the infected mice. On the strength of these data and noting their oral bioavailabilities, we propose that the 4-anilinoquinazoline and pyrrolopyrimidine scaffolds of lapatinib, CI-1033, and AEE788 are worth optimizing againstT. bruceiin medicinal chemistry campaigns (i.e., scaffold repurposing) to discover new drugs against HAT.

scholarly journals Evaluating 5-Nitrofurans as Trypanocidal Agents

2013 ◽  
Vol 57 (4) ◽  
pp. 1638-1647 ◽  
Author(s):  
Christopher Bot ◽  
Belinda S. Hall ◽  
Guzmán Álvarez ◽  
Rossanna Di Maio ◽  
Mercedes González ◽  
...  
Keyword(s):  
Human African Trypanosomiasis ◽  
Bloodstream Form ◽  
Type I ◽  
Biochemical Screening ◽  
African Trypanosomiasis ◽  
Open Chain ◽  
Content Type ◽  
Growth Inhibitory ◽  
Initial Activation

ABSTRACTThe nitroheterocycle nifurtimox, as part of a nifurtimox-eflornithine combination therapy, represents one of a limited number of treatments targetingTrypanosoma brucei, the causative agent of human African trypanosomiasis. The mode of action of this prodrug involves an initial activation reaction catalyzed by a type I nitroreductase (NTR), an enzyme found predominantly in prokaryotes, leading to the formation of a cytotoxic unsaturated open-chain nitrile metabolite. Here, we evaluate the trypanocidal activities of a library of other 5-nitrofurans against the bloodstream form ofT. bruceias a preliminary step in the identification of additional nitroaromatic compounds that can potentially partner with eflornithine. Biochemical screening against the purified enzyme revealed that all 5-nitrofurans were effective substrates forT. bruceiNTR (TbNTR), with the preferred compounds having apparentkcat/Kmvalues approximately 50-fold greater than those of nifurtimox. For several compounds,in vitroreduction by this nitroreductase yielded products characterized by mass spectrometry as either unsaturated or saturated open-chain nitriles. When tested against the bloodstream form ofT. brucei, many of the derivatives displayed significant growth-inhibitory properties, with the most potent compounds generating 50% inhibitory concentrations (IC50s) around 200 nM. The antiparasitic activities of the most potent agents were demonstrated to be NTR dependent, as parasites having reduced levels of the enzyme displayed resistance to the compounds, while parasites overexpressing TbNTR showed hypersensitivity. We conclude that other members of the 5-nitrofuran class of nitroheterocycles have the potential to treat human African trypanosomiasis, perhaps as an alternative partner prodrug to nifurtimox, in the next generation of eflornithine-based combinational therapies.

Protein-tyrosine Kinase p72 syk Is Activated by Platelet Activating Factor in Platelets

1994 ◽  
Vol 72 (06) ◽  
pp. 937-941 ◽  
Author(s):  
Karim Rezaul ◽  
Shigeru Yanagi ◽  
Kiyonao Sada ◽  
Takanobu Taniguchi ◽  
Hirohei Yamamura
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Critical Role ◽  
Platelet Activating Factor ◽  
Kinase Assay ◽  
Potential Candidate ◽  
Protein Tyrosine ◽  
Induced Aggregation

SummaryIt has been demonstrated that activation of platelets by platelet-activating factor (PAF) results in a dramatic increase in tyrosine phosphorylation of several cellular proteins. We report here that p72 syk is a potential candidate for the protein-tyrosine phosphorylation following PAF stimulation in porcine platelets. Immunoprecipitation kinase assay revealed that PAF stimulation resulted in a rapid activation of p72 syk which peaked at 10 s. The level of activation was found to be dose dependent and could be completely inhibited by the PAF receptor antagonist, CV3988. Phosphorylation at the tyrosine residues of p72 syk coincided with activation of yllsyk. Pretreatment of platelets with aspirin and apyrase did not affect PAF induced activation of p72 syk .Furthermore, genistein, a potent protein-tyrosine-kinase inhibitor, diminished PAF-induced p72 syk activation and Ca2+ mobilization as well as platelet aggregation. These results suggest that p72 syk may play a critical role in PAF-induced aggregation, possibly through regulation of Ca2+ mobilization.

L-selectin stimulation of canine neutrophil initiates calcium signal secondary to tyrosine kinase activation

1997 ◽  
Vol 272 (3) ◽  
pp. H1302-H1308 ◽  
Author(s):  
E. Crockett-Torabi ◽  
J. C. Fantone
Keyword(s):  
Tyrosine Kinase ◽  
Reperfusion Injury ◽  
Protein Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Ischemia Reperfusion Injury ◽  
Leukocyte Adhesion ◽  
Ischemia Reperfusion ◽  
Second Messengers ◽  
Cross Linking ◽  
Calcium Signal

Neutrophils play an important role in myocardial ischemia-reperfusion injury. Neutrophil adhesion to the vascular endothelium is one of the important early mechanisms that lead to reperfusion injury. The leukocyte adhesion molecule, L-selectin, plays a major role in the initial interaction between neutrophils and endothelial cells. Intervention aimed at blocking selectins or their associated ligands can exert cardioprotective effects. The purpose of this study was to examine the role of L-selectin in the initiation of transmembrane signaling and regulation of canine neutrophil responses. Cross-linking of canine neutrophil L-selectin using anti-L-selectin antibody induced a rapid and transient increase in intracellular Ca2+ levels and superoxide anion generation that were dependent on the extent of L-selectin cross-linking. The responses were significantly inhibited by the protein tyrosine kinase inhibitor, genistein. The results demonstrate that ligation of canine neutrophil L-selectin is coupled to intracellular signal transduction pathways and the generation of second messengers, which may independently play important regulatory roles in modulating neutrophil-endothelial cell interactions.

Oxidative stress-induced cell death of human oral neutrophils

2003 ◽  
Vol 284 (4) ◽  
pp. C1048-C1053 ◽  
Author(s):  
Eisuke F. Sato ◽  
Masahiro Higashino ◽  
Kazuo Ikeda ◽  
Ryotaro Wake ◽  
Mitsuyoshi Matsuo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Tyrosine Kinase ◽  
Protein Tyrosine Kinase ◽  
Caspase 3 ◽  
Nuclear Dna ◽  
Kinase Inhibitor ◽  
Tissue Injury ◽  
Morphological Changes ◽  
Limited Information ◽  
And Function

Polymorphonuclear leukocytes (PMN) play crucial roles in protecting hosts against invading microbes and in the pathogenesis of inflammatory tissue injury. Although PMN migrate into mucosal layers of digestive and respiratory tracts, only limited information is available of their fate and function in situ. We previously reported that, unlike circulating PMN (CPMN), PMN in the oral cavity spontaneously generate superoxide radical and nitric oxide (NO) in the absence of any stimuli. When cultured for 12 h under physiological conditions, oral PMN (OPMN) showed morphological changes that are characteristic of those of apoptosis. Upon agarose gel electrophoresis, nuclear DNA samples isolated from OPMN revealed ladder-like profiles characteristic of nucleosomal fragmentation.l-cysteine, reduced glutathione (GSH), and herbimycin A, a protein tyrosine kinase inhibitor, suppressed the activation of caspase-3 and apoptosis of OPMN. Neither thiourea, superoxide dismutase (SOD), nor catalase inhibited the activation of caspase-3 and apoptosis. Moreover, N-acetyl-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-CHO), inhibitor for caspase-3, inhibited the fragmentation of DNA. These results suggested that oxidative stress and/or tyrosine-kinase-dependent pathway(s) activated caspase-3 in OPMN, thereby inducing their apoptosis.

scholarly journals New Drugs for Human African Trypanosomiasis: A Twenty First Century Success Story

2020 ◽  
Vol 5 (1) ◽  
pp. 29 ◽  
Author(s):  
Emily A. Dickie ◽  
Federica Giordani ◽  
Matthew K. Gould ◽  
Pascal Mäser ◽  
Christian Burri ◽  
...  
Keyword(s):  
Oral Therapy ◽  
Human African Trypanosomiasis ◽  
First Century ◽  
New Drugs ◽  
World Health ◽  
African Trypanosomiasis ◽  
Twenty First Century ◽  
Health Organization ◽  
Stage 1 ◽  
Competing Priorities

The twentieth century ended with human African trypanosomiasis (HAT) epidemics raging across many parts of Africa. Resistance to existing drugs was emerging, and many programs aiming to contain the disease had ground to a halt, given previous success against HAT and the competing priorities associated with other medical crises ravaging the continent. A series of dedicated interventions and the introduction of innovative routes to develop drugs, involving Product Development Partnerships, has led to a dramatic turnaround in the fight against HAT caused by Trypanosoma brucei gambiense. The World Health Organization have been able to optimize the use of existing tools to monitor and intervene in the disease. A promising new oral medication for stage 1 HAT, pafuramidine maleate, ultimately failed due to unforeseen toxicity issues. However, the clinical trials for this compound demonstrated the possibility of conducting such trials in the resource-poor settings of rural Africa. The Drugs for Neglected Disease initiative (DNDi), founded in 2003, has developed the first all oral therapy for both stage 1 and stage 2 HAT in fexinidazole. DNDi has also brought forward another oral therapy, acoziborole, potentially capable of curing both stage 1 and stage 2 disease in a single dosing. In this review article, we describe the remarkable successes in combating HAT through the twenty first century, bringing the prospect of the elimination of this disease into sight.

scholarly journals The expression of COX-2 in VEGF-treated endothelial cells is mediated through protein tyrosine kinase

2002 ◽  
Vol 11 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Pravit Akarasereenont ◽  
Kitirat Techatraisak ◽  
Athiwat Thaworn ◽  
Sirikul Chotewuttakorn
Keyword(s):  
Endothelial Cells ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Protein Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Kinase C ◽  
Protein Kinase C Inhibitor ◽  
Cox 2 ◽  
Cox 1

Cyclooxygenase (COX), existing as the COX-1 and COX-2 isoforms, converts arachidonic acid to prostaglandin H2, which is then further metabolized to various prostaglandins. Vascular endothelial growth factor (VEGF) has been shown to play important roles in inflammation and is upregulated by the prostaglandin E series through COX-2 in several cell types. Here, we have investigated the effects of VEGF on the COX isoform expressed in human umbilical vein endothelial cells (HUVEC). The signalling mechanism of the COX isoform expressed in endothelial cells activated with VEGF will be also investigated using the tyrosine kinase inhibitor, genistein, and protein kinase C inhibitor, staurosporine. The activity of COX2 was assessed by measuring the production of 6-keto-prostaglandin F1α in the presence of exogenous arachidonic acids (10 μM, 10 min) by enzyme immunoassay. The expression of COX isoform protein was detected by immunoblot using specific antibodies. Untreated HUVEC contained no COX-2 protein. In HUVEC treated with VEGF (0.01-50 ng/ml), COX-2 protein, but not COX-1, and COX activity were increased in a dose-dependent manner. Interestingly, the increased COX-2 protein and activity in response to VEGF (10 ng/ml) was inhibited by the tyrosine kinase inhibitor, genistein (0.05-5 μg/ml), but not by the protein kinase C inhibitor, staurosporine (0.1-10 ng/ml). Thus, the induction of COX-2 by VEGF in endothelial cells was mediated through protein tyrosine kinase, and the uses of specific COX-2 inhibitors in these conditions, in which VEGF was involved, might have a role.

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